Tracing microplastics in rural drinking water in Chongqing, China: Their presence and pathways from source to tap.

Despite the significant attention given to microplastics in urban areas, our understanding of microplastics in rural drinking water systems is still limited. To address this knowledge gap, we investigated the presence and pathways of microplastics in rural drinking water system, including reservoir, water treatment plant (WTP), and tap water of end-users. The results showed that the treatment processes in the WTP, including coagulation-sedimentation, sand-granular active carbon filtration, and ultrafiltration, completely removed microplastics from the influent. However, the microplastic abundance increased during pipe transport from WTP to residents' homes, resulting in the presence of 1.4 particles/L of microplastics in tap water. This microplastic increase was also observed during the transportation from the reservoir to the WTP, suggesting that the plastic pipe network is a key source of microplastics in the drinking water system. The main types of polymers were PET, PP, and PE, and plastic breakdown, atmospheric deposition, and surface runoff were considered as their potential sources. Furthermore, this study estimated that rural residents could ingest up to 1034 microplastics annually by drinking 2 L of tap water every day. Overall, these findings provide essential data and preliminary insights into the fate of microplastics in rural drinking water systems.

Robust Assembly of Cross-Linked Protein Nanofibrils into Hierarchically Structured Microfibers.

Natural, high-performance fibers generally have hierarchically organized nanosized building blocks. Inspired by this, whey protein nanofibrils (PNFs) are assembled into microfibers, using flow-focusing. By adding genipin as a nontoxic cross-linker to the PNF suspension before spinning, significantly improved mechanical properties of the final fiber are obtained. For curved PNFs, with a low content of cross-linker (2%) the fiber is almost 3 times stronger and 4 times stiffer than the fiber without a cross-linker. At higher content of genipin (10%), the elongation at break increases by a factor of 2 and the energy at break increases by a factor of 5. The cross-linking also enables the spinning of microfibers from long straight PNFs, which has not been achieved before. These microfibers have higher stiffness and strength but lower ductility and toughness than those made from curved PNFs. The fibers spun from the two classes of nanofibrils show clear morphological differences. The study demonstrates the production of protein-based microfibers with mechanical properties similar to natural protein-based fibers and provides insights about the role of the nanostructure in the assembly process.

Millions of microplastics released from a biodegradable polymer during biodegradation/enzymatic hydrolysis.

In this article, we show that enzymatic hydrolysis of a biodegradable polyester (poly(ε-caprolactone)) by Amano Lipase PS in an aqueous (buffer) environment yielded rapidly an excessive number of microplastic particles; merely 0.1 g of poly(ε-caprolactone) film was demonstrated to yield millions of particles. There were also indications of non-enzymatic hydrolysis at the same conditions, but this did not yield any particles within the time frame of the experiment (up to 6 days). Microplastic particles formed had irregular shapes with an average size of around 10 µm, with only a few reaching 60 µm. The formation of microplastic particles resulted from the uneven hydrolysis/erosion rate across the polymer film surface, which led to a rough and undulating surface with ridge, branch, and rod-shaped micro-protruding structures. The consequent detachment and fragmentation of these micro-sized protruding structures resulted in the release of microplastics to the surroundings. Together with microplastics, hydrolysis products such as acidic monomers and oligomers were also released during the enzymatic hydrolysis process, causing a pH decrease in the surrounding liquid. The results suggest that the risk of microplastic pollution from biodegradable plastics is notable despite their biodegradation. Special attention needs to be paid when using and disposing of biodegradable plastics, considering the enormous impact of the paradigm shift towards more biodegradable products on the environment.

Microplastics generated from a biodegradable plastic in freshwater and seawater.

Biodegradable polymers have been regarded as a promising solution to tackle the pollutions caused by the wide use of conventional polymers. However, during the biodegradation process, the material fragmentation leads to microplastics. In this work, the formation of microplastics from biodegradable poly (butylene adipate-co-terephthalate) (PBAT) in different aquatic environments was investigated and compared with the common non-biodegradable low-density polyethylene (LDPE). The results showed that a much larger quantity of plastic fragments/particles were formed in all aquatic environments from PBAT than from LDPE. In addition, UV-A pretreatment, simulating the exposure to sunlight, increased the rate of PBAT microplastic formation significantly. The size distribution and shapes of the formed microplastics were systematically studied, along with changes in the polymer physicochemical properties such as molecular weight, thermal stability, crystallinity, and mechanical properties, to reveal the formation process of microplastics. This study shows that the microplastic risk from biodegradable polymers is high and needs to be further evaluated with regards to longer timeframes, the biological fate of intermediate products, and final products in freshwater, estuarine and seawater natural habitats. Especially, considering that these microplastics may have good biodegradability in warmer 20 - 25° water but will most likely be highly persistent in the world's cold deep seas.

Microplastics Originating from Polymer Blends: An Emerging Threat?

No one can have missed the growing global environmental problems with plastics ending up as microplastics in food, water, and soil, and the associated effects on nature, wildlife, and humans. A hitherto not specifically investigated source of microplastics is polymer blends. A 1 g polymer blend can contain millions to billions of micrometer-sized species of the dispersed phase and therefore aging-induced fragmentation of the polymer blends can lead to the release of an enormous amount of microplastics. Especially if the stability of the dispersed material is higher than that of the surrounding matrix, the risk of microplastic migration is notable, for instance, if the matrix material is biodegradable and the dispersed material is not. The release can also be much faster if the matrix polymer is biodegradable. The purpose of writing this feature article is to arise public and academic attention to the large microplastic risk from polymer blends during their development, production, use, and waste handling.

Protection and Prevention of Age-Related Hearing Loss.

Presbycusis is a sensorineural hearing loss caused by hearing system aging and degeneration. The clinical manifestations are progressive bilateral symmetrical hearing loss, and the hearing curve is mostly slope-shaped with high-frequency reduction, sometimes flat. The results of the second national sample survey of disabled persons (2006) showed that the total number of hearing and speech disability in China was 27.8 million, accounting for 34% of the total number of disabled people in China. Among them are people over 60 years old. There are 20.4541 million people with hearing disabilities. There are 9.49 million senile deaf patients, accounting for 34.1% of the total number of hearing disabilities. As society gradually becomes aging, the incidence of presbycusis is getting higher and higher. The study of its pathogenesis is of great significance for the diagnosis, treatment, and prevention of presbycusis. The rapid progress of molecular biology experimental technology has provided us with a new opportunity to fully understand and reveal the presbycusis. In the near future, early diagnosis of presbycusis-related genes and early prevention or delay of the occurrence and development of presbycusis will become a reality.

Efficient soluble deep blue electroluminescent dianthracenylphenylene emitters with CIE y (y ≤ 0.08) based on triplet-triplet annihilation.

It has been challenging to develop deep blue organic molecular fluorescent emitters with CIE y (y ≤ 0.08) based on triplet-triplet annihilation (TTA). Here, we report facilely available dianthracenylphenylene-based emitters, which have a 3,5-di(4-t-butylphenyl)phenyl moiety at the one end and 4-cyanophenyl or 3-pyridyl at the other end, respectively. Both fluorophores show a high glass transition temperature of over 220 °C with a thermal decomposition temperature of over 430 °C at an initial weight loss of 1%. The preliminary characterizations of the organic light-emitting diodes (OLEDs) that utilized these nondoped emitters provided high EQEs of 4.6%-5.9% with CIE coordinates (0.15, 0.07-0.08). The analysis of the EL transient decay revealed that TTA contributed to the observed performance. The results show that the new emitters are attractive as a potential TTA-based host to afford stable deep blue fluorescent OLEDs.